Relating to lenses

ABSTRACT

A method of spacing an object from a mould for the formation of a multi-layered polymer. The method comprises: attaching at least one spacer to the object; attaching the at least one spacer to the mould; and adding material to the mould to form the multi-layered polymer.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/139,936, filed Jan. 21, 2021; the content of which are herebyincorporated by reference.

TECHNICAL FIELD

The present invention relates to improvements in the manufacture oflenses formed using a combination of a monomer and an object. The objectmay be a foil, a lens, a thin display, or any other such object. Morespecifically, it relates to lenses whereby the monomer material is castaround the object.

BACKGROUND ART

Lens formation can be a complicated process. This is especially the casewhere lenses are formed in a layered manner using a film or foil, suchas PMMA, and a cast lens material, such as a UV-curable monomer. Castlenses with embedded films can be produced applying a well-known methoddescribed hereafter. Details of the method described in the backgroundsection will be known to the skilled person, and thus the description islimited to a general overview of the process. Such processes have manydrawbacks, which the present application seeks to overcome.

A foil is provided, the foil having a curved surface. The foil may beformed of many different materials, such as TAC, PC, PA, PMMA or PET.The foil is then placed on a holder in order to allow the positioning ofthe foil relative to a mould. The mould is made up of two parts, a frontmould and a back mould.

It is required to space the foil accurately with respect to one or bothof the moulds. For ease of explanation, it will be assumed for thepresent example that the foil is being positioned relative to the frontmould. Attachment dots are therefore used to hold the foil staticrelative to the mould. These attachment dots, typically of an adhesiveor curable compound, are placed on the foil, and are then brought intocontact with the front mould, with the foil the desired distance fromthe front mould and the attachment dots in contact with the front mould.There are a variety of options as to how to correctly position the foil,but one example is that the foil may include a flat portion thatsurrounds the curved portion of the foil, and the fiat portion isbrought into contact with a corresponding portion of the front mould.The attachment dots are then allowed to solidify, either by setting ofthe adhesive or by curing of the curable compound.

Once the attachment dots are solid and holding the foil in place, theholder can be removed and the back mould can be brought into positionopposing the front mould and forming a space between the foil and theback mould. The front mould and back mould are then connected aroundtheir circumferences to form a mould cavity within which is positionedthe foil. A curable monomer is then added into the mould cavity to castthe lens. Once in position, the monomer can be cured, forming themulti-layered lens. Removal of the lens from the mould can then beperformed in any well-known way.

STATEMENTS OF INVENTION

According to a first aspect, there is provided a method of spacing onobject from a mould, for the formation of a multi-layered polymer,comprising:

-   -   attaching at least one spacer to the object;    -   attaching the at least one spacer to the mould; and    -   adding monomer to the mould; and    -   curing the monomer to form the multi-layered polymer.

This provides an improved method for ensuring that an object iscorrectly spaced from a mould, during a manufacturing process. As willbe clear from the detailed description below, the order of the steps ofattaching the spacer to the object and attaching the spacer to the mouldare immaterial to the operation of the invention and therefore theirorder in the claim is not intended to be limiting. The use of spacersover attachment dots also removes the requirement for the use of aprecise spacing machine, as dots must be custom-produced for each unit,whilst spacers may be mass-produced.

The object may for example be a foil, a lens, a display (in particular athin display), or any other similar such object.

The object may be received within one or more notches or recesses in theat least one spacer.

The at least one spacer may include a protrusion onto which the objectis received. The object may be secured to the at least one spacer bydeforming the protrusion once the object is received on the at least onespacer.

The object, may be secured to the spacer. For example, adhesive, spotwelding, a fastening device such as a screw, or other such means may beused.

The at least one spacer may be secured to the mould. For example,adhesive, spot welding, a fastening device such as a screw, applicationof a vacuum, or other such means may be used.

The step of curing the monomer may be achieved by the application of UVradiation or by a thermal curing process.

The method may further comprise the step of removing the at least onespacer after curing the monomer.

Alternatively, the at least one spacer may be retained as a part of themulti-layer polymer.

The at least one spacer may be seated around the mould. The at least onespacer may include a recess or abutment into or against which the mouldmay be received.

According to a second aspect, there is provided a system for theformation of a multi-layered polymer, the system comprising:

-   -   a spacer configured to receive an object and hold it in a fixed        position relative to a mould;    -   wherein the mould is configured to receive a monomer around the        object, for the creation of the multilayered polymer.

The object may comprise one of a foil, a lens, a display, or othersimilar object.

The object may be received within one or more notches or recesses in theat least one spacer.

The spacer may include a protrusion onto which the object is received.

The object may be secured to the at least one spacer by deforming theprotrusion once the object is received on the at least one spacer.

The object may be secured to the at least one spacer, for example byadhesive, spot welding, a fastening device, application of a vacuum, orother such means.

The at least one spacer may be seated around the mould, The at least onespacer may include a recess or abutment into or against which the mouldmay be received.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments will now be described in detail with reference tothe accompanying drawings, in which:

FIG. 1 is a schematic view of an assembly for spacing foil from a mould;

FIG. 2 is a flow chart of a method of spacing foil from a mould;

FIG. 3 is a flow chart of a further method of spacing foil from a mould;

FIGS. 4 and 5 are schematic views of a further assembly for spacing foilfrom a mould; and

FIG. 6 is a schematic view of a further assembly for spacing foil from amould.

DETAILED DESCRIPTION

When manufacturing a lens using foil and a second material, such as amonomer, bonded to the foil, it is necessary to be able to space thefoil from a mould before the monomer is filled in the mould cavity. Oneexample of a suitable process to space the foil from a mould is:

-   -   1. Adhesive material is dispensed on the foil    -   2. The foil is placed at the desired distance from a mould with        the adhesive material wetting both the mould and the foil    -   3. The adhesive material is cured, generally by application of a        UV light source

This three-step process results in the foil being held at the desireddistance from the mould while the monomer is filled in the mould cavityto create the lens. The adhesive material may be dispensed and hardenedin a stepwise manner, with alternate steps of dispensing and hardening.This will be achieved in a similar way to described in the background ofthe present specification. However, rather than using a single adhesivedot in each position between the foil and the mould, each attachment dotmay be cured and then an additional attachment dot deposited on top of acured attachment dot, to allow greater heights to be achieved.

As an alternative method of spacing the foil, a method is proposed asdescribed below and depicted in FIGS. 1 to 6.

In a first embodiment 100, described in FIGS. 1 and 2, rather than usinga dispensed adhesive material, one or more spacers 102 are firstattached S102 to the foil 104. The spacers 102 may be attached to thefoil 104 using notches 106, into which the foil 104 is received. Thespacer or spacers 106 may also be secured to the foil 104, for exampleusing an adhesive, point welding, or another such means. The spacers 102are then inserted S104 into the mould or moulds 108, and may be attachedto the mould or moulds 108. Example methods of attaching the spacers 106to the moulds 108 include adhesive or the application of a vacuum. Oncein position, a monomer may be inserted S106 within the mould cavity toform the lens, with the foil being held in place by the spacer(s). Themonomer will then be cured S108, generally by the application of UVlight or by an increase in temperature (thermal curing), depending onthe properties of the monomer(s). A polymer sample enclosing the samplefoil will then be able to be extracted from the mould. The spacers maythen be removed. In some embodiments, the spacers may be retained as apart of the finished product.

In some embodiments, as shown in FIG. 3, rather than first securing thefoil to the spacer and then attaching the spacer and foil to the mould,the spacer may be attached S202 to the mould and then the foil may beattached S204 to the spacer. Hence, it is apparent that the order ofsteps is not necessarily intrinsic to the disclosed method. In thismethod, the monomer is then added S206 and cured S208, as in FIG. 2.FIG. 3 also has an additional step of removing the spacer S210. This maybe included in any embodiment, where desired. However, in someembodiments, the spacer or spacers may be retained with the finishedpolymer product.

In a further embodiment, shown in FIGS. 4 and 5, the spacers 202 arefirst attached to the mould 208 and then the foil 204 is introduced ontothe spacers 202. In this embodiment, the spacers 202 include protrusions210 that are received into corresponding holes 212 in the foil 204. Oncethe foil 204 has been received onto the spacers 202, the foil 204 issecured by heating to soften or melt the spacers 202 such that theprotrusions 210 of the spacers 202 may be deformed to secure the foil204 in position. In similar embodiments, rather than securing the foilby deforming the end, i.e., the protrusions, of the spacer, additionalmaterial may be added. For example, adhesive may be applied onto thespacer and foil, or a screw or other attachment means may be utilised.

A further embodiment utilises more massive spacers 302, 402, shown inFIG. 6. The spacers 302, 402 in this embodiment resemble a ring. In thisarrangement, the spacers 302, 402 therefore are seated around the mould308 rather than be attached thereto. The spacers 302, 402 are thereforeshaped to receive the mould 308, in order to hold the mould 308 in thedesired position. FIG. 6 shows two different possibilities for how themould 308 could be held by the spacers 302, 402.

On the left side, a recess 312 is formed in the spacer 302, into whichthe mould 308 is seated. A second recess 314 is also formed in thespacer 302 in order to receive the foil 304. As with previousembodiments, the order in which the foil 304 and mould 308 areintroduced to the spacer 302 is not imperative. The mould 308 and foil304 may further be secured by additional means, as mentioned in relationto previous embodiments.

On the right side, the spacer 402 abuts the mould 308, using an,abutment 416. Although the abutment 416 is shown as a lateral protrusionfrom the spacer 402, the abutment 416 may instead be the same width asthe remainder of the spacer 402 and therefore need not protrude. Thecontact of the abutment 416 with the mould 308 ensures that the mould308 is maintained in the desired position relative to the spacer 402.The foil 304, meanwhile, is received within a small notch 406, similarlyto FIG. 1, rather than into the large recess 314 shown on the left sideof FIG. 6.

As noted above, whilst each embodiment here discusses the use of a foilwith a spacer, the foil may be replaced with any other object, such as alens, a thin display, a hologram, a logo, or other similar such objects,and therefore the use of the term “foil” in the specific description isnot intended to be limiting to the invention as a whole.

As will be clear to the skilled person, any method or arrangement forlocating the mould in any embodiment may be combined with any method orarrangement for locating the spacer, and the specific arrangements arenot limited to the combinations disclosed herein.

1. A method of spacing an object from a mould, for the formation of amulti-layered polymer, comprising: attaching at least one spacer to theobject; attaching the at least one spacer to the mould; and addingmaterial to the mould to form the multi-layered polymer.
 2. The methodof claim 1, wherein the object comprises one of a foil, a lens, adisplay, or other similar object.
 3. The method of claim 1, wherein theobject is received within one or more notches or recesses in the atleast one spacer.
 4. The method of claim 1, wherein the at least onespacer includes a protrusion onto which the object is received.
 5. Themethod of claim 4, wherein the object is secured to the at least onespacer by deforming the protrusion once the object is received on the atleast one spacer.
 6. The method of claim 1, wherein the object issecured to the at least one spacer, for example by adhesive, spotwelding, a fastening device, or other such means.
 7. The method of claim1, wherein the at least one spacer is secured to the mould, for exampleby adhesive, spot welding, a fastening device, application of a vacuum,or other such means.
 8. The method of claim 1, wherein the step ofcuring the monomer is achieved by the application of UV radiation or bya thermal curing process.
 9. The method of claim 1, further comprisingthe step of removing the at least one spacer after curing the monomer.10. The method of claim 1, wherein the at least one spacer is retainedas a part of the multi-layer polymer.
 11. The method of claim 1, whereinthe at least one spacer is seated around, the mould.
 12. The method ofclaim 11, wherein the at least one spacer includes a recess or abutmentinto or against which the mould is received.
 13. A system for theformation of a multi-layered polymer, the system comprising: a spacerconfigured to receive an object and hold it in a fixed position relativeto a mould; wherein the mould is configured to receive a monomer aroundthe object, for the creation of the multilayered polymer.
 14. The systemof claim 13, wherein the object comprises one of a foil, a lens, adisplay, or other similar object.
 15. The system of claim 13, whereinthe object is received within one or more notches or recesses in the atleast one spacer.
 16. The system of claim 13, wherein the at least onespacer includes a protrusion onto which the object is received.
 17. Thesystem of claim 16, wherein the object is secured to the at least onespacer by deforming the protrusion once the object is received on the atleast one spacer.
 18. The system of claim 13, wherein the object issecured to the at least one spacer, for example by adhesive, spotwelding, a fastening device, or other such means.
 19. The system ofclaim 13, wherein the at least one spacer is secured to the mould, forexample by adhesive, spot welding, a fastening device, application of avacuum, or other such means.
 20. The system of claim 13, wherein the atleast one spacer is seated around the mould, optionally wherein the atleast one spacer includes a recess or abutment into or against which themould is received.